Synthetic fuel production from cottonseed: Fast pyrolysis and a TGA/FT-IR/MS study

• Thermal decomposition behaviour of cottonseed and qualification of evolved gases are analysed by TGA-FTIR-MS.
• Cottonseed is converted to bio-fuel via one step thermal treatment-fast pyrolysis.
• Bio-oil yield of nearly 50% is reached and calorific value of bio-oil is as twice of the raw material.
• Chromatographic characterization showed that aliphatic subfraction shows many similarities with standard diesel.

This study investigates the thermal decomposition behavior of cottonseed via TGA/FT-IR/MS and the quantification/characterization of liquid products from fast pyrolysis. Thermal degradation of the biomass sample has occurred in four steps, corresponding to the removal of moisture, decomposition of cellulose, hemicellulose and lignin and it was completed at about 700 °C. The main gaseous products evolved were CO2, light hydrocarbons and H2O. For the fast pyrolysis experiments, particular investigated process variables were temperature (400–700 °C), heating rate (5–700 °C min−1) and nitrogen gas flow rate (100–800 cm3 min−1). Maximum oil yield was attained at 500 °C with a yield of 49.5% under 200 cm3 min−1 nitrogen flow rate and at a heating rate of 300 °C min−1. Bio-oil obtained at optimum conditions are separated into its fractions by column chromatography. The oil and its sub-fractions were characterized by elemental analysis, FT-IR, and GC/MS. The char was characterized with elemental analysis and FT-IR techniques. The aliphatic sub-fraction of the obtained bio-oil contains predominantly straight chain of n-alkanes and alkenes. According to the chemical characterization, the bio-oil can be utilized as conventional liquid fuels.